In basketball, a block (short for blocked shot) occurs when a defender deflects or stops a field goal attempt without committing a foul. The top 25 highest blocks totals in NCAA Division I men's basketball history are listed below. The NCAA did not split into its current divisions format until August 1973. From 1906 to 1955, there were no classifications to the NCAA nor its predecessor, the Intercollegiate Athletic Association of the United States (IAAUS). Then, from 1956 to spring 1973, colleges were classified as either "NCAA University Division (Major College)" or "NCAA College Division (Small College)". Blocks are a relatively new statistic in college basketball, having only become an official statistic beginning with the 1985–86 season.